The present invention relates to a detecting and monitoring device for observing a picture image. According to the invention, the detecting and monitoring device prevents flickering from occurring and prevents emitting a flash from an emitting device without recording normally.
The present invention also relates to a detecting and monitoring device for observing a picture image which is a picture taken by a color video camera under a flash light generated by a stroboscope or other emitting device and played back as a still picture.
In a field of industrial instrumentation and medical industry, a detecting and monitoring device is utilized in a system for photographing a detected object and observing a motion picture and a still picture of the detected object displayed on a monitor. Such a conventional system is shown in FIG. 1.
As shown in FIG. 1, a color video camera or a video camera 01 takes a picture of a detected object 02 and outputs a picture signal V thereof. The picture signal V is transmitted to a monitor 04 through a still picture recording and playback device 03 and displayed as a motion picture. The still picture recording and playback device 03 includes a semi-conductor memory device or a magnetic floppy device. The still picture recording and playback device 03 is capable of recording and playing back a picture signal for one frame (picture signal for one field or one frame) from the picture signal V.
The still picture recording and playback device 03, a stroboscope 06, a variety of sensors 07 and a pushbutton switch 08 are connected to a controller 05, respectively. The sensors 07 detect conditions of the detected object 02 such as a position of the detected object 02. Usually, one of the sensors 07 and the pushbutton switch 08 is selectively operated.
An operation and a function of the system will be described as follows.
For example, when the detected object 02 is moved along a direction of an arrow as shown in FIG. 1, the detected object 02 is displayed as motion picture on the monitor 04. While an operator observes a display on the monitor 04, the operator pushes the pushbutton switch 08 at a moment when a picture scene suitable for a still picture comes into the display. The stroboscope 06 emits a flash under the control of the controller 05, and the picture signal V for one scope including the image picture illuminated with the flash is simultaneously recorded as information in the still picture recording and playback device 03.
During a predetermined interval after the pushbutton switch 08 pushed, for example, 5 seconds, picture images are not transmitted from the color video camera 01 to the monitor 04 and the picture signal for one scope recorded in the still picture recording and playback device 03 is repeatedly reproduced and transmitted to the monitor 04. Thus, the image picture of the detected object 02 taken by the color video camera 01 when the pushbutton switch 08 is pushed is displayed as a still picture on the monitor 04.
After the predetermined interval, the picture image signal output from the color video camera 01 is transmitted to the monitor 04 again and the monitor 04 displays the detected object 02 as a motion picture. Also, the still picture recording and playback device 03 is reset to record other pictures. For example, in a still picture recording and playback device 03 having a magnetic floppy device, a magnetic head is moved to the next track position.
In case that a still picture is observed when the detected object 02 is approached to a detected point, the sensors 07 detect a position of the detected object 02 and output a detecting signal and an operation is started which is similar to the operation started by the pushbutton switch 08.
The above described detecting and monitoring device usually employs a white balance adjusting function. White balance adjustment is an adjustment for adjusting an output signal from the color video camera 01 in accordance with the color temperature of the detected object 02. That is, the picture signal from the color video camera 01 is adjusted so as to clearly reproduce a white object as a white detected object.
FIG. 2 shows a conventional automatic white balance circuit for adjusting the white balance of the picture signal. When the automatic white balance switch (not shown) is operated, sample and hold circuits 09B, 09R as shown in FIG. 2 become in sampling condition and then a feedback group is operated. Each output signal G, R, B from the color video camera 01 is clamped at clamp circuits 010G, 010R, 010B, respectively. Peak white level of each output signals G, R, B is detected by peak wave detector circuits 011G, 011R and 011B, respectively. In comparators 012R and 012B, levels of output signals G and R and levels of output signals G and B are compared, respectively. A RC voltage and BC voltage are fed back to white balance adjusting amplifiers 013R, 013B in accordance with a result of the comparisons of signals, and are set in accordance with gains of the RC voltage and the BC voltage are adjusted to be equal to the levels of signals G, R, B which are output signals from the white balance adjusting amplifiers 013G, 013R and 013B, respectively. After completing white balance adjustment, the white balance switch is turned off and the sample and hold circuits 09B and 09R hold the voltage amount at that time. Hereafter, white balance adjusted signals are obtained based on the RC voltage and the BC voltage held in the sample and hold circuits 09B, 09R.
In a system of frame record by recording odd number field signals and successive even number field signals as picture image signals for one scope, reproducing and transmitting two field signals recorded by frame record to the monitor 04, and displaying the picture image with the two field signals interlaced with the one signal, there is a problem of occurring flicker. The flicker occurs due to a difference of brightness of the odd number field signal and the even number field signal. Even if the difference of the brightness is about 1% thereof, human eyes still feel such a difference as "flicker". In case that one field signal is recorded as the picture image signal for one scope and the picture image signal is reproduced and transmitted recorded one field signal as the signal for one scope to the monitor, the flicker has not occurred in principle.
An occurrence of such a flicker and the degree of the occurrence depend on operation modes and kinds of image pickup elements of the video camera 01, a relation between emitting timing of the stroboscope 06 and photographing timing of the video camera 01 and a recording method (frame recording or other recording method).
In the above described conventional device, the stroboscope 06 generates a flash according to a request from the controller 05 whenever the pushbutton switch 08 is pushed; nevertheless, the still picture recording and playback device 03 is not set in recording condition or the picture image signal V is not set output from the video camera 06. Under the above condition, the picture image can not be recorded. After the still picture recording and playback device 03 is reset correctly, the pushbutton switch 08 is pushed again to emit a flash from the stroboscope 06 and the still picture is recorded in the still picture recording and playback device 03 so as to record the picture image.
Some detected objects dislike being illuminated under flash light several times. In medical industry field, it is desirable to decrease illuminated times for caring a patient who does not want to be inconvenienced. However, in the conventional device, the emitting device emits a flash even if the still picture can not be recorded.
Conventionally, the white balance is adjusted in a mode of taking a motion picture (hereinafter so called as "motion picture mode"). In the motion picture mode, a flash is not generated by the stroboscope 06. On the other hand, the object is illuminated by the stroboscope 06 in a mode of taking a picture for storing picture signal V into the still picture recording and playback device 03 (hereinafter so called as "still picture mode").
Accordingly, color temperature of the object in the moving picture mode is different from that in the still picture mode. If a picture of the object is in the still picture mode and the picture is controlled by the white balance adjustment circuit based on the color temperature in the moving mode, it is a problem that the color of the reproduced picture image is different from the real color of the object.
The purpose of the invention is to provide a detecting and monitoring device by observing picture images in which flicker is prevented from occurring.
Another purpose of the invention is to provide a detecting and monitoring device by observing a picture image in which a flash is not generated unnecessarily.
Another purpose of the invention is to provide a detecting and monitoring device by observing a picture image in which a white balance adjustment is suitably operated according to the changing color temperature of an object.